Firearms, such as M-16 and AR-15 rifles, are often used with accessories, such as scopes, sights, lasers, and grenade launchers. Typically, such accessories are associated with the firearm via a rail. The rail may include a number of mounting projections interleaved with a series of grooves, and these mounting projections and grooves may be employed to associate the accessory with the rail. Rails are known in the firearm industry and usually conform to certain standards defined by, for example, the U.S. government. For example, two common rails include the “Picatinny” rail and the “Weaver” rail, which both include interleaved mounting projections and grooves, but differ in dimension.
To associate an accessory with a rail, a device known as a “throw lever” may be used. A typical throw lever includes a clamping portion and a lever arm portion. The lever arm portion may be actuated to selectively clamp the throw lever to the rail, or to release the throw lever from the rail. For example, the throw lever may be clamped about one or more of the mounting projections.
In some cases, the lever arm portion of the throw lever may directly move the clamping portion into abutment against the rail. In other cases, the lever arm portion may indirectly act on the clamping portion via an intervening cam. The cam may transfer movement of the lever arm portion to the clamping portion, forcing the clamping portion into abutment against the rail.
Conventional throw levers may be problematic. For example, if the lever arm portion catches on or snags against an external object, the throw lever may open and may detach from the rail. For this reason, some firearm operators take the precaution of tethering the accessory to the firearm using a rope, so that the accessory is not lost if the throw lever opens.
Also, conventional throw levers may malfunction. For example, in cases in which the throw levers include a lever arm portion that directly moves the clamping portion, the clamping portion may be inclined to rub against and abrade the rail, which in time may impair the security of the connection. Such abrasion may be less problematic when the lever arm portion indirectly moves the clamping portion via an intervening cam, but in such cases the cam is typically exposed, such that dust and debris can become lodged about the cam and interfere with the operation of the throw lever.
Conventional throw levers also may not securely connect the accessory to the firearm. For example, some throw levers apply a clamping force to a relatively small portion of the rail, creating a connection that is relatively less secure than the connection that could be created by clamping to a relatively larger portion of the rail. This problem may be exacerbated by the relatively complex geometry of the mounting projection because many throw levers may be adapted to come in contact with only a small percentage of the mounting projection surface.
Conventional throw levers also may be difficult to operate. For example, attaching the throw lever to the rail may require two hands, leaving the firearm operator without a hand available to hold the firearm. Further, operating the throw lever may require an awkward hand motion. The throw lever may not be suited for use with accessories calibrated to a particular axial location along the rail, such as a scope. The throw lever may be able to slide along the rail when the lever arm portion is in an open position, which may require the firearm operator to manually position the throw lever along the rail at a selected axial position. For this reason, it may be difficult to reposition the throw lever in the same axial position on the rail after the throw lever has been removed, which is an issue with accessories such as scopes that are calibrated for a particular rail location.